After Seb defiantly dives into the pool in preparation for a competition, Seb emerges, much to his father Tony's relief. However, in the changing rooms shortly afterwards, Seb clutches his chest in pain and suddenly collapses.

Rushed to resus, Yuki's mortified when he realises that he almost missed a vital medical sign in Seb's diagnosis. When Tony arrives to see his son, Yuki delivers the devastating news that Seb has been suffering from leukaemia.

As Yuki fumbles around attempting to administer treatment, he learns that Seb's been covering his symptoms by taking aspirin in order to continue diving. Yuki reveals to Seb that he may eventually need a heart transplant and with that, Seb pulls Yuki to him and whispers something in his ear. Yuki's taken aback by the revelation.